Chapter 9 manual computation of gradients integer division...

[dataforager]

Chapter 9 manual computation of gradients integer division...

[ageron]

Hi @dataforager,

Thanks for your feedback! Indeed, I wrote this code for Python 3, which defaults to float division. However, everything should work fine in Python 2 as well if you add the following line at the beginning of your Python files:

# To support both python 2 and python 3
from __future__ import absolute_import, division, print_function, unicode_literals

The Jupyter notebooks include this line at the very beginning, so they actually work fine in both Python 2 and 3.

Since Python 2 is now deprecated, I recommend switching to Python 3, or at least preparing for it. One way to prepare for migration is to start writing code that works on both Python 2 and Python 3. Some libraries like six or future can help a lot. In fact, I recommend you go through this excellent Python 2/3 compatibility cheat sheet. It shows how to write code that works on both Python 2 and 3.

The starting point is to add the from __future__ line above at the beginning of all your Python files, then run your tests and fix all the errors you find: you will likely need to replace a few / with // if you expect integer division, you will need to fix all your print statements (e.g. replace print "hi" with print("hi"), and so on), and most importantly you will need to fix a bunch of unicode vs byte string errors. But once that's done your code will be much easier to migrate to Python 3, when the time comes.

That said, I think you are right that the book should mention this fact. Right now it just says "The latest version of Python 3 is recommended. Python 2.7+ should work fine too, but it is deprecated." I will add "If you use Python 2, you must add from __future__ import division, print_function, unicode_literals at the beginning of your Python files."

I hope this helps,
Aurélien